1. Field of the Invention
The present invention relates to an image scanning device which scans a document and outputs a scanned image corresponding to an image on the document. More particularly, the present invention relates to an image scanning device in which an image sensor is cleaned to prevent degradation of the scanned image due to contamination of the image sensor.
2. Description of the Related Art
Typically, an image scanning device is employed to scan a document and then output the scanned image to an external appliance. Additionally, an image scanning device can be incorporated in an appliance such as copy machine or multifunctional machine to instantaneously print a scanned image generated in the image scanning device and print the scanned image onto a print media.
FIG. 1 shows a multifunctional machine 100 capable of implementing an image printing function as an example of an electronic appliance which employs an image scanning device as mentioned above. FIG. 2 shows a conventional image scanning device 200. Referring to FIGS. 1 and 2, a conventional image scanning device 200 includes a scanner body 210 for supporting a flat glass plate 220 on which a document to be scanned is laid. A sensor unit 250 is installed within the scanner body 210 and is capable of reciprocating along a travel route provided underneath the flat glass plate 220. The sensor unit 250 includes a light source (not shown) for illuminating light toward the document, an image sensor 255 for reading the light L reflected from the document and generating a scan image, and a carrier 251 installed so as to reciprocate along the travel route which carries the image sensor 255. It is possible to employ any suitable image sensor such as CCD (Charge Coupled Device) or a CIS (Contact Image Sensor) as the image sensor 255. The scanned image outputted from the image sensor 255 is either outputted to the outside of the composite machine 100 or outputted to an image forming unit 150 provided within the composite machine 100 and then used for printing an image corresponding to the scanned image on a print medium P fed from a paper-feeding device 160.
One drawback of the above-mentioned device is that the incident face 256 of the image sensor 255, into which face the light reflected from the document is incident, can be contaminated. The image sensor 255 can be contaminated by external substances such as soil D (see FIG. 2) or dust. These external substances are introduced from the exterior through a connection part of each component or toner particles may leak out from the image forming unit 150 at the time of printing. In particular, in an image scanning device of the line scan type, which scans document while the sensor 250 is moving, electrostatic forces are produced by friction between the sensor unit 250 and other components when the sensor unit 250 moves. Therefore, dust and toner particles may be draw in, thereby accelerating the contamination of the image sensor. Additionally, since the image scanner 255 is positioned within the scanner body 251, it is relatively difficult to clean. Consequently, the quality of the scanned image can deteriorate due to the contamination of the image sensor.
Accordingly, there is a need for an improved image scanning device in which an image sensor can be cleaned automatically and internally to prevent a scanned image from degrading due to image sensor contamination.